Recent Progress in the Field of Artificial Organs

A recent Scientific Reports study moves vascular tissue engineering forward by showing that a fully 3D-bioprinted, large-diameter blood vessel can survive and remodel in vivo. Many existing approaches to making vascular conduits rely on synthetic scaffolds or decellularized tissues. In contrast, scaffold-free methods use layers of living cells that naturally produce their own extracellular matrix, which can reduce foreign-body reaction and improve biocompatibility. This study builds on those principles using an extrusion-based bioprinting system combined with a rotating mandrel that does not alter cell behavior or proliferation. The technique provides a straightforward way to fabricate cylindrical conduits of varying diameters and lengths. Constructs composed of rat smooth muscle cells and fibroblasts were printed to resemble small artery–sized aortas, showing uniform geometry, circumferential cellular alignment, and physiologic mechanical properties. For in vivo evaluation, animals received the conduits within 24 h of incubation. Implantation involved infrarenal aortic cross-clamping, excision of a 10-mm aortic segment, and end-to-end anastomosis. Patency was inferred from animal survival, as occlusion would rapidly cause hemodynamic collapse. Only one rat died, attributed to cross-clamp–induced ischemia rather than graft failure. Animals were euthanized at postoperative days 7, 30, and 60. Across timepoints, the grafts remained patent, showed minimal inflammation, and integrated well with host tissue. The authors note that maintaining multilayer, scaffold-free bioprinted vessels in vivo for up to 60 days represents the longest successful implantation of its kind. Potential applications include treating diabetic limb ischemia, arteriosclerosis, creating arteriovenous fistulas, and pediatric vascular reconstruction where growth-compatible grafts are needed. Overall, this work represents a promising step toward clinically relevant, living vascular replacements.—BFC. Melero-Martin, J. M., et al. Development and deployment of a functional 3D-bioprinted blood vessel. Scientific Reports 15, Article 93276 (2025). Severe burns and traumatic injuries often require skin grafting, but current approaches typically replace only the epidermis. While this can provide temporary coverage, it does not restore the deeper dermis, which houses the blood vessels, nerves, and extracellular matrix essential for elasticity, strength, and long-term function. As a result, patients are left with significant scarring and limited restoration of normal skin architecture. Researchers at Linköping University in Sweden have developed two complementary bioprinting strategies designed to recreate thick, living skin. The first creates a 3D-printable gel containing dermal cells distributed throughout a supportive matrix. When implanted under the skin of mice, these printed tissues supported cell survival and triggered the production of collagen and other components of healthy dermis. A second technology enables the incorporation of simple, customizable channels formed by temporary hydrogel structures that can be positioned within the printed tissue and later dissolved, leaving behind open pathways for vascular ingrowth. By distributing these channels throughout the construct, oxygen and nutrients can reach deeper layers of the graft, reducing cell loss and enabling the formation of larger tissues. Together, these approaches represent a new class of 3D-printed grafts capable of regenerating not only the epidermis but the deeper dermal layer as well. Future work aims to scale the technology to human-sized wounds and to test its performance in real wound environments. The findings mark a promising step toward patient-specific grafts generated from small skin biopsies. Beyond burn care, this work adds to the growing set of strategies aimed at solving the vascularization challenge in engineered tissues, an essential step in enabling larger, perfused constructs that can support fully implantable tissues and organs.—BEW. https://liu.se/en/news-item/skin-in-a-syringe-a-step-towards-a-new-way-to-heal-burns. Restoring hepatic metabolism while controlling inflammation in acutely decompensated cirrhosis remains a major unmet clinical need. A research team from the Institute of Science Tokyo recently published their work using whole-blood extracorporeal circuit, termed the UTOpiA system, that combines human leukocyte antigen (HLA)–depleted liver organoids with granulocyte-monocyte apheresis (GMA) to treat acute-on-chronic liver failure (ACLF) and acute liver failure (ALF). The goal was to replicate critical liver functions while avoiding the immune rejection risks that have limited prior bioartificial liver systems. The platform circulates whole blood through a bioreactor containing HLA-depleted liver organoids capable of performing key metabolic tasks, including ammonia detoxification, lactate clearance, protein synthesis, and bile acid processing. In parallel, the system uses GMA—a selective removal of activated granulocytes and monocytes—to reduce the intense inflammatory response that drives early mortality in both ACLF and ALF. Using two rat models of ALF and ACLF, the authors show that this dual-action approach improved biochemical parameters, stabilized hemodynamics, and in some cases reversed organ failure without the need for transplantation. Because the organoids are HLA-depleted, they elicited minimal allogeneic immune activation, raising the possibility of an “off-the-shelf” biologic liver support device. If validated in larger trials, this combined metabolic–immunomodulatory extracorporeal system could mark a significant advance toward functional bioartificial liver platforms capable of bridging patients to recovery or transplant.—JAT. Yamaguchi H., Yoneyama Y., Ichimura K., et al. Reversal of ACLF and ALF using whole blood extracorporeal system combining HLA-depleted liver organoids with granulocyte-monocyte apheresis. Journal of Hepatology. Published online October 2025:S0168827825024778. doi: 10.1016/j.jhep.2025.08.038. Worldwide, rheumatic heart disease affects more than 24 million people and causes over 200 000 deaths per year. The associated morbidity, mortality, and financial burden are particularly significant in low- and middle-income countries, including Southeast Asia, sub-Saharian Africa, and Oceania, and among younger patients. However, the optimal choice of a prosthetic valve remains debated, especially in patients under 65 years of age. Mechanical valves offer the advantage of potential lifetime durability but are associated with a lower quality of life compared with biological valves, which, in turn, have limited durability and often require multiple reoperations. Synthetic polymer leaflet materials, such as those used in the Tria Mitral Valve (Foldax), aim to address the root cause of biological prothesis failure—namely, calcification and immunologic reactivity—by employing a novel proprietary, nonanimal-based polymeric material derived from sixolane and polyurethane technologies. The prospective, single-arm, multicenter Clinical Investigation for the Foldax Tria Mitral Valve–India evaluated the safety and performance of this novel valve in adult patients with moderate to severe mitral valve stenosis and/or regurgitation. The Tria Mitral Valve demonstrated significant benefits in clinical, echocardiographic, and functional outcomes, with an acceptable safety profile through 1-year follow-up. Further investigations are underway to fully assess the potential of this polymer valve to improve quality of life in childbearing women and in patients with rheumatic disease.—AB. https://www.jacc.org/doi/10.1016/j.jacc.2025.06.017 Stanford Medicine researchers have developed a novel transplant approach combining blood stem cells and pancreatic islet cells from immunologically mismatched donors that completely prevented or cured Type 1 diabetes in mice. The approach generates a hybrid immune system containing both donor and recipient cells, which re-educates the immune response to accept transplanted islets while concomitantly halting autoimmune attacks on native islets. None of the animals developed graft-versus-host disease, and treated mice did not require immunosuppressive drugs or insulin for the six-month study duration. Noteworthy, in total, 19 out of 19 animals were protected from diabetes, and nine out of nine with established disease were cured. This strategy builds on previous studies using partial bone marrow chimerism to promote tolerance in organ transplantation, but uniquely addresses autoimmune-mediated diabetes. The pre-transplant regimen includes antibodies, low-dose radiation, and a drug targeting autoimmunity, all of which are already clinically used in human blood stem cell transplantation. Researchers are now exploring clinical translation, including ways to expand donor islet availability using pluripotent stem cells and improve graft survival. Beyond diabetes, this gentler immune-reset approach may enable stem cell transplantation for autoimmune diseases and non-cancerous blood disorders, as well as promote tolerance in mismatched solid organ transplants. The study was published online November 18 by Bhagchandani et al. in the ‘Journal of Clinical Investigation’ and funded by the NIH, Stanford Bio-X, the Reid Family, the H.L. Snyder Foundation, Elser Trust, and the Stanford Diabetes Research Center.—JDU. https://www.news-medical.net/news/20251118/New-transplant-approach-resets-the-immune-system-to-stop-Type-1-diabetes.aspx. The authors declare no conflicts of interest.